Method of making a hydrotherapy tank liner

ABSTRACT

A plastic film hydrotherapy tank liner having conduits therein adapted to be apertured and connected to a source of pressurized gas so that hydrotherapy liquid contained therein is agitated by the gas passing through. The conduits are made by folding a sheet of plastic film so that it resembles, in section, an M-shaped article, then heat sealing the two spaced folds of the folded sheet to provide the conduits, one terminal end of each being then closed by heat sealing.

United States Patent Robert C. Miller Elgln, 111.

Feb. 18 1970 Nov. 2, 1971 Borg-Warner'Corporatlon Chicago, 111.

[72] Inventor [21] Appl. No. [22] Filed [45] Patented [73] Assignee [54] METHOD OF MAKING A HYDROTIIERAPY TANK LINER 1 Claim, 2 Drawing Figs.

[51] Int.C|. [50] FieldoISearch [56 References Cited UNITED STATES PATENTS 1,081,987 12/1913 Price, Jr. 4/173 2,758,624 8/1956 Krause et a1. 156/227 X 3,420,227 l/l969 Voorlas 4/180 3,485,694 12/1969 Bauder et a1 156/227 Primary Examiner-Reuben Epstein Atrorneys- Donald W. Banner, William S. McCurry and John W. Butcher ABSTRACT: A plastic film hydrotherapy tank liner having conduits therein adapted to be apertured and connected to a source of pressurized gas so that hydrotherapy liquid contained therein is agitated by the gas passing through. The conduits are made by folding a sheet of plastic film so that it resembles, in section, an M-shaped article, then heat sealing the two spaced folds of the folded sheet to provide the conduits, one terminal end of each being then closed by heat sealmg.

METHOD OF MAKING A HYDROTHERAPY TANK LINER BACKGROUND OF THE INVENTION Devices for use in hydrotherapy tanks in which the hydrotherapy liquid is agitated are known in the art. A common type of device is a series of conduits on a pad having preselected holes therethrough through which a pressurized gas, such as air, passes to agitate the liquid closely adjacent thereto. Such pads are placed in the bottom of the tank and are reusable and thus when used in a hospital are sterilized for each patient.

Another type of more recent vintage is a disposable liner having conduits attached thereto. They require an assembly of parts in that the conduits must be attached by cement or a suitable pressure-sensitive tape.

According to this invention a disposable hydrotherapy tank liner with integral conduits is fabricated from a single sheet of a plastic film. The film is folded longitudinal, so that approximately one half overlies the other. Then each of the halves is folded away from the other to form a pair or folds spaced from the first fold. A cross section of this folded sheet approximates that of the letter M. A narrow joint of plastic along each of the folds is then heat sealed to provide longitudinally extending conduits or channels and one end of each conduit or channel is closed by being heat sealed.

ln use the open ends of the conduits or channels are joined to a source of pressurized gas and holes are punched open in the conduits for the passage of gas thereto. When the liner is placed in its position of use and liquid is flowed thereinto, the liquid adjacent the holes will be agitated by the gas.

THE DRAWINGS FIG. 1 shows a plastic sheet folded in the shape of the letter M with the heat sealed portions being therein indicated; and

FIG. 2 shows the tank liner unfolded ready for use with the channels shown thereon.

THE PREFERRED EMBODIMENT The drawings illustrate a sheet of a plastic film l folded centrally as at 12 with each half of the centrally folded sheet folded outwardly as at 14 and 16 to form folds l8 and 20. The sheets are heat sealed along lines '22 and 24. to form conduits or channels 26 and 28, respectively, which are closed as at 30 and 32. When in use the opened ends of the conduits 26 and 28 are attached to a source of gas and openings such as indicated at 34 are selectively made in the conduits 26 and 28 for the passage of the gas thereto which agitates the hydrotherapy liquid in the liner.

There are at least three requirements on the plastic used for the tank liner:

A. Safety. No potentially harmful compounds may be leached or otherwise removed from the plastic under conditions of use. This places certain limits on plasticizers and pigments. It need only be remembered that nerve endings are essentially exposed in burn cases, for example, and free acid radicals could hurt. Moreover, the plastic surface should be no more slippery than the present stainless steel now used for hydrotherapy tanks, in order to avoid slips and falls when patients are entering and leaving the tank.

B. Physical strength. Sufficient strength to resist tearing and accidental puncturing are necessary. The liner must also be flexible to conform to the tank shape.

C. Cost. Since the liner is disposable, cost is evidently an important factor.

Plastic films of polyethylene of about 0.001 inch to 0.008 inch and above in thickness have proved to be successful and can be used. As long as puncture and tear resistance remain high, thin films are preferred from the standpoint of flexibility and cost. Low density, no-slip polyethylene without added has been found to be less slippery than stainless steel when wet.

In addition to polyethylene films, polyvinyl chloride films can be used. In all cases, the requirements set out above must be considered.

What is claimed is:

1. A method of making a plastic film hydrotherapy tank liner which comprises:

folding a sheet of plastic along a center line thereof so that approximately one half of the sheet overlies the other half;

folding each of said halves away from each other to form a pair of folds spaced from the first fold;

heat sealing a narrow band of the plastic along each of said pair of folds to provide conduits or channels;

heat sealing one end of each channel;

whereby when the sheet is unfolded in a hydrotherapy tank,

there are provided spaced channels extending in one direction and spaced inwardly of the edges of the sheet, said open end of each channel being adapted for connection to a source of gas and said conduits being adapted to be selectively opened at desired locations for the passage of therethrough. 

